Toric-lens series and process of making same



K L. w. BUGBEE. Y TORIC LENS`SERIES AND PROCESS 0F MAKING SAME'.

ARPLICAIION FILED. NOV. l2, 19.20. V

Patented Aug. 15, 19.22.l

4 SHEETS-SHEET l,

Hq E y A TTORNEYS.

L. w. BUGBEE. TORIC LENS SERIES AND PROCESS 0F MAKING SAME.

APPLICATION FILED NOV. l2, 1920... I 1,426,146' Patented Aug. 15, 1922.

4 SHEETS-#SHEET 4.

ATTORNEYS.

-uirsu sTAEs M rsNr OFFICE.

LUCIAN W. BUGBEE, or INDIANAPOLIS, INDIANA, AssIGNoR 'ro 'ONEPIECE 31mg,LENS COMPANY, oF INDIANAPOLIS, INDIANA, A CORPORATION TOEIC-LENS SERIESAND PROCESS OF MAKING SAME.

Specification of Letters Patent.. Patented Aug. 15, 1922.

Apnncation filed November 12, 1920. serial No. 423,669.

To aZZ 'whom t may concer/n:

Be it known that I, LUCIAN W. BUGBEE, a citizen of the United States,and a resident of Indianapolis, county of Marion, and State of Indiana,have invented a certain new and useful Toric-Lens Series and Process ofMaking Same; and I do hereby declare that the following is a full,clear, and eXact description thereof, reference being had to the.

accompanying drawings, in which like numerals refer to like parts.

This invention relates to a series of ophthalmic lenses of toric typehaving a constant base curve on the concave sides thereof and the convexsurfaces thereof being toric with their curvatures in one principalmeridian, called herein the equatorial curvature, varying according tothe thickness of the lenses so that the lenses of the series will havesubstantially the same power and to the process of making the same;- ysubstantially the same power is meant the same power within reasonablecommercial limits.

The above is a statement of the generic vention, but a specific.invention, that par- ""mcularly shown and described herein, relates tosuch a series of toric lenses having substantially the same power butwith varying curvatures in the other principal meridian, termed hereinthe meridional curvature.

The process of making said toric lens series, broadly stated, consistsfirst in forming on theconcave sides of said lenses a uniform basecurvature, say of six dioptrics, and afterwards grinding and finishingthe convex surfaces in toric form,` and particularly.

by mounting the lens blanks of the* series Awith'nthe concave sidessecured upon the periphery of spotting wheels `ofuniform diameter andgrinding the toric surfaces with grinding tools or stones for giving tothe same the desired meridional curvature in one principal meridian,while the varying thicknesses of the blanks or lenses mounted on saidspotting wheel produce the desired equatorial curvatures in the otherprincipal meridian. Thus where a series of grinding tools or stones areused having varying meridional curvatures in one principal meridian,varying thicknesses of the lenses will result and that will determinethe equatorial curvatures in the other principal meridian of the seriesof lenses.

sphere Varying cylinders or cylindrical curvatures, when such process isemployed,

varies the thickness of the lenses, and the thickness of the lensesvaries the spheres or spherical curvatures, and the lenses havepractically the same power throughout their entlre area. The series oftoric lenses constituting this inventlon are relatively more nearlyperfect than toric llenses made by processes heretofore employed.'Reference may brieiy be made to the three types of toric lensesresultlng from three processes heretofore used 1n the art. Qne may becalled the prevailing type of toric lens, the process of which isfamillar to all skilled in the art of making ophthalmic lenses. Theselenses can only be made right for one thickness of lens and they becomeless nearly perfect as the thickness of the lens increases. The power oftheprevailing type of toric lens, when the wearer looks other thanradially through them, is very different from the original prescriptionfor reasons known to those skilled in the a'rt and which need not herebe stated.

Another type of toric lens is the 'onepiecebifo'cal lens, called in thetrade Ultex lens, as represented by the distance portion thereof. Inthis type of toric -lens the deep curve eiect is preserved land itspower is more nearly uniform regardless of the angle at which one looks,than in the prevailing type of toric lenses. l

Still a third type -of toric lenses is what is called in the trade the"Punktal lens, where each curve in thetoric is calculated for anindividual prescription, but in the manufacture of these lenses a toolfor each prescription is required and they must'be made one at a time,so that they cannot be made in a'large way like the prevailing type oftoric lens.

The new toric lens constituting this present invention has practicallyallof the advantages of all three of the toric lenses above described.llt can be made commercially in large quantities as well and as cheaplyas the prevailing type of torio lenses and at the same time it preservesthe deep curve effect of the distance portion of the Ultex onepiecebifocal lens, and it is practically as good theoretically as the Punktallens.

rllhe means for carrying out said process is substantially the same asset forth in my former applications Serial No. 275,789, filed February8, 1919, for spotting wheel for making toric lenses, and Serial No.276,190, filed February 10, 1919, for process of makin toric lenses.

he full nature of the invention will be understood from the accompanyingdrawings and the following description and claims:

ln the drawings, Fig. 1 is a side elevation of means which may beemployed for carrying out the process herein set forth and for makingthe series of toric lenses constituting this invention, they lower partsof the machine being broken away. Fig. 2 is a plan view of Fi 1. Fig. 3is a vertical section of a portion of F1g. 1 on the line 3-3 and on anenlarged scale. Fig. 4c is a similar section with thicker lens blanks orlenses on a spottingwheel of the same di ameter as in Fig. 3, but with agrinding wheel ofsharper transverse curvature. Fig. 5 is a plan view ofa portion ofv Fig. 2 on a larger scale. Fig. 6 is a similar view withthicker lenses or blanks and a grinding wheel with a sharper transversecurvature. Fig. 7 illustrates sections through the series of toriclenses made according to the process set forth herein, the upper rowshowing the spheres or equatorial curvatures and the lower row showingthe cylinders or meridional curvatures of the same lenses.

ln' the drawings, 10 is the table of a 1 -achine with an oppositelylocated pair of posts 11 in which a grind stone 12 or other suitablegrinder for ophthalmic lenses is mounted so as to rotate. rlhe peripheryof the grind stone has a concave transverse curvature adapted to grindthe lenses so as to give to them the predetermined cylinder ormeridional curvature. Themeans for rotating the grinder 12 is not shown,as mechanism for rotating the same is well known in the art.

A spotting wheel 20 is 'mounted on an arbor 21 carried by a pair ofsupports 22 pivoted at their lower ends on a pivot shaft 23 in thebearing blocks 24 secured to the table 10 adjacent the periphery of thegrind stone. A weighted arm 25 is rigidly connected with the pivot shaft23 and extends towards the grind stone and has a weight 26 on its outerend. The weighted armA yieldingly forces the spotting wheel towards andin engagement with the periphery of the grind stone, and said grindstone and spotting wheel are tangentlal of each other, as is more fullypresented and eX- plained in my former application Serial No. 276,539,filed February 12, 1919, for lens grinding machine.

The spotting wheel is made of metal and rectangular seats are cut in theperiphery of the wheel to receive the lens blanks 3() thereon. A. gear32 is secured on the shaft 21 to which ower is transmitted for rotatingthe spottlng wheel.

rllhe first step in the process consists in rinding and finishing theconcave sides of t e lens blanks to the desired base curvature, say, sixdioptrics. rllhen the blanks are secured accurately and uniformly on thespotting wheel so that. theirl anterior sides will be ground by thegrind stone 12. as the machine is operated.

'llhe sphereor equatorial curvature will, in a general way, bepredetermined by the diameter of the spotting wheel, but more accuratelyspeaking, by the distance from the axis of the spotting wheel to theanterior or outer surfaces of the lenses. An increase in the radius ofthe spotting wheel will cause a corresponding decrease in the equatorialcurvature, and the thicker the lenses secured upon a certain spottingwheel, the less will be said equatorial curvature.

ln carrying out thls process, by means herein illustrated, a singlespotting wheel (or spottin wheels of the same diameter) is employe but aplurality of grinding wheels or elements are used for making the series,the transverse concave curvature of the periphery of the grinding wheelsor elements varying, that is, increasing in curvature. rllhus, as shownin Figs. 2 and 3, the grind stone or element' has a certain transversecurvature which will give a certain cylinder or meridional curvature tothe lenses ground. In Fig. 4, a grinding element with a sharpertransverse curvature is shown, cooperating with the same size ofspotting wheel so that a stronger cylinder will be ground having asharper meridional curvature. @ther grinders are used having stillsharper transverse curvatures until the whole series is completed.

1n rinding sharper meridional curvatures, 1t is obvious that relativelythicker lenses are produced, or, in other words, thicker glass must beused in order to allow for the sharper meridional curvatures, rllheadded thickness of the lenses for the sharper meridional curvatures orstronger cylinders, therefore, will have their anterior surfaces moreremote from the axis of the spotting wheel than the lenses with slightermeridional curvatures, so that the equatorial c-urvatures or Asphereswill be reduced or weakened correspondingly. Hence, the lenses of thedifferent series thus formedv with such spotting wheel and series ofgrinders with varying transverse curvatures will differ from each otherin their meridional curvatures, according to the transverse curvaturesof the series of grinders and in their equatorial curvatures accordingto the differences in the thickness of the lenses or glass and,therefore, according to the differences in the meridional curvatures.

Such a series of torio lenses is illustrated in Fig. 7 there being fourlenses shown in the series. The concave sides of all these lenses are ofthe same curvature. The equatorial curvatures of the different lenses inthe series gradually decrease. The meridional curvatures in such seriesgradually increase. It is noted also that the differences in theequatorial curvatures of the lenses in said series are directly relatedto the differences in the thickness of the lenses and also to theydifferences in the meridional curvatures thereof.

In Fig. 7 thefcurvatures are Fshown exaggerated in order to illustratethe same. The first lens in the upper row illustrates the equatorialcurvature and the one below it the meridional curvature of the samelens, and the same is true of the second, third and fourth lenses shownin the rows.

As stated, one series of lenses consists of all curvatures that can bemade with one spotting wheel and a plurality or series ofv grinders withdifferent transverse curvatures. The number in the series may be greator small, as desired, but a series with a considerable number ofvariations in the meridional curvature and corresponding equatorialcurvatures must be ordinarily made and kept in stock by jobbers andopticians.

The automatic lessening of the equatorial curvatures by reason of theincrease in thickness of the lenses, as a series is made, beginning withthe grinding of a slight transverse curvature, and continuing with thegrinding of gradually increasing transverse curvatures, causes theseries as a whole to remain more nearly within the limits of theoreticalperfection as to the form of said lenses whereby the have the combinedvirtues of all three kinds of .torio lenses heretofore referred to,namely, the.prevailing type of `toric lens, the distance surface of theUltex bifocal lenses, and the Punktal lenses, and has not the objectionsto said prior lenses. Furthermore, the lenses constituting thisinvention can. be made by this process very rapidly, and practically ascheaply as the ordinary prevailing type of toric lenses, .wherefore thisinvention con stitutes an advance in the artof toric lenses and themanufacture thereof/of considerable importance.

The chief characteristics of the toric lenses consisting of the seriesare three, namely, that they al1 have substantially the same lens powerywithin commercial limits, and the same base curve on the concave side,and also their curvatures in one principal meridian on the convex sidesvary according to the thickness of the lenses. The lens series with saidcharacteristics results from the process set forth herein, and the chiefnovel features of the process consist of two steps or operations,namely, forming the concave sides of the series of lenses with a uniformbase curve, and formingthe convex surfaces so as to be toric with theircurvatures in lone principal meridian varying according to the thicknessof the lenses. The first one of these two steps, namely, forming auniform base curve, is not in itself new, having for a great many yearsbeen a characteristic in the manufacture of onepiece bifocal lenses madeunder the Conner patents and afterwards called Ultex lenses. The secondstep or operation in making this series of lenses is new and the totalprocess, therefore, is new. The result which follows from thecombination of these two steps or operations is givingl to such seriesof lenses a uniform lens power.

The invention claimed is:`

1. A toric lens series of varying thickness having substantially thesame power and having a constant base curve on the concave l .sidesthereof and convex 'torio surfaces on the convex sides with theircurvatures in one principal meridian varying according to the thicknessof the lenses. A

2. A toric lens series of varying thickness having substantially thesame power and having a constant base curve on the concave sides thereofand the convex surfaces having a series of varying curvatures in onepr1ncipal meridian with their curvatures in the other principal meridianvarying according and finishing the concave sides thereof with aconstantv curvature, mounting the same upon a spotting wheel of uniformdiameter, and apply grinding lelements of varying meridional curvaturesto the ex- -terior surfaces of the lenses for grinding the same, wherebythe thickness and they meridional curvatures of said lenses will' varyaccording to the transverse. curvatures of the grinding element ofvaryingmerid- E Meanies ional curvatures, and the equatorial curvatureswill depend upon the radius of the spotting Wheel and the thickness ofthe glassand whereby the lenses of the Series 5 will have substantiallythe same power.

5. A torio lens series of varying thickness, having substantially thesame power and having a constant base curvature on the concave sidesthereof, and toric surfaces on the convex sides with their curvatures inone l@ principal meridian varying inversely with the thickness of thelenses.

In Witness whereof, li have hereunto affixed my signature.

LUC/IAN W. BUGBEE

